A/C clutch only spins when I jump the relay

Tiny
AUGIE DELIA
  • MEMBER
  • 1997 CHEVROLET TRUCK
  • 4WD
  • AUTOMATIC
  • 280,000 MILES
I recently replaced the compressor due to a slight leak. I recharged the system and have adequate pressure but not the clutch won’t engage. When I jump the relay, it works and the air gets cold but once I pull the jumper, nothing. I have tested the relays and gotten a new one and it doesn’t work. Looking for any help I can get.
Saturday, October 16th, 2021 AT 4:21 AM

5 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good morning,

I would double-check your work. The high-pressure switch at the bottom of the compressor may be the issue. Check for voltage with the key on. You should have power on both terminals with the switch plugged in.

https://www.2carpros.com/articles/car-air-conditioner-not-working-or-is-weak

I attached the wiring diagram for you of the system. The connector of the switch was an issue back in the day. Without that signal from that switch, the relay will not close and allow compressor operation.

https://www.2carpros.com/articles/how-to-check-wiring

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Roy

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Saturday, October 16th, 2021 AT 6:03 AM
Tiny
AUGIE DELIA
  • MEMBER
  • 9 POSTS
Thank you! If that was the issue wouldn’t it still not work when I jumped the relay?
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Saturday, October 16th, 2021 AT 11:29 AM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Nope, the relay sends direct power to the clutch.

Without the proper signal from the switch, the control side of the relay will not energize.

Roy
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Saturday, October 16th, 2021 AT 11:50 AM
Tiny
AUGIE DELIA
  • MEMBER
  • 9 POSTS
Do I need to completely remove the compressor and remove all the Freon from the system to check this?
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Saturday, October 16th, 2021 AT 12:28 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
No, it is at the back at the bottom. It is tough to get to but take your time.

Roy
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Saturday, October 16th, 2021 AT 1:19 PM

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